1. Field of the Invention
The present invention relates to control, monitoring, and protection devices for environmental conditioning systems including heating, ventilation, air conditioning and refrigeration systems (“HVACR systems”).
2. Description of the Related Art
Prior HVACR control devices monitor line voltage, line current, and other parameters such as temperature to determine the state of an HVACR system component, such as a compressor. For example, such a device may monitor line current and in the event excess current is detected, for example from a locked motor rotor, the control device will shut down the system. When the control device detects a fault and shuts down the system, a technician typically must physically inspect components of the HVACR system to determine the cause of the fault.
Generally, each separate control device detects a fault after failure of a system component. For example, a direct short sensed by a motor current monitoring device after motor overheating has caused breakdown of the winding insulation, or no heating or cooling capacity detected by a pressure sensor after refrigerant blockage or loss that reduces efficiency. Detection of such faults often does not occur until additional damage has occurred, requiring system shut down until repairs are complete.
Control devices may include limits relating to system parameters, for example, desired temperature, motor current, and pressure. Control devices, for example a circuit card, are generally located within a housing for the HVACR system; therefore, determining and adjusting limits or other aspects of parameters stored by the control device generally requires cumbersome access.